If he were to prove this under lab conditions he could make a killing.
Thankfully, it appears people with impure motivation are incapable of the discipline required to achieve something like this. If you watch the video, this is made explicit near the middle. Chang only undertook filming because he thought the footage would be used for research, and not displayed in any kind of “promotional” way. He never once took payment from any of the many thousands he healed in his lifetime. Additionally, in the second half of the footage, he is under quite extensive scientific scrutiny, scanned for hidden metal, asked to demonstrate at a location randomly chosen by the scientists, connected to voltage- and amperage-meters, etc.